Model of ARgon Low Energy Yield (MARLEY)
Developed at UC Davis, MARLEY is the first realistic model of neutrino electron interactions on argon for enegies less than 50 MeV. This includes the energy range important for supernova burst neutrinos and also solar 8-Boron neutrinos.
MARLEY uses a semi-empirical model of experimentally-derived nuclear matrix elements for the reaction 40-Ar + νe -> 40-K* + e- These Gamow-Teller (GT) and Fermi (F) matrix elements are published in experiments that looked at the analog decay of 40-Ti [M.Bhattacharya, et al PRC 58 (1998)], and forward (p,n) scattering[Bhattacharya et al. PRC 80 (2009)]. The matrix elements are then incorporated into a theoretical model (Hauer-Feshbach) to predict the level density for states above the binding energy of 40-K.
The resulting cross-section is shown below. Since the two different matrix element extraction methods give slightly different results, both are selectable in the MARLEY model software package.
MARLEY interaction in DUNE
MARLEY generated events for DUNE are more realistic than in previous simplistic models. Not only do transitions take place to many more known levels, but transitions to levels above the binding enegy of 40-K now can de-excite by particle emission and not just electons and gammas. A typical simulated MARLEY event is shown below.